Android彈窗中的spinner異常解決辦法

彈窗常用AlertDialog來襪，因為AlertDialog可以很方便的添加所要的項。比如確定/取消按鈕，自定義的標題欄、自定義的信息布局等。在自定義布局時，比如我們采用LinearLayout來布局，然後再往LinearLayout中添加一些項，比如TextView、EditText等。這些都很容易實現。

不過，如果添加spinner，可能就會出問題了。找了很久，發現是context引起的。因為spinner在點擊展開下拉列表時，需要依賴於窗體，而使用context只是提供了一個上下文，並沒有提供窗體，所以會造成錯誤。下面是已實現的代碼：

package com.sparkle;

import Android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.graphics.Color;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;

public class Contury {

 private Activity _activity = null;
 private Context _context = null;
 private Spinner _spinner = null;

 public Contury(Activity activity) {
  _activity = activity;
  _context = activity; 
 }

 private LinearLayout GenerateLinearLayout(int orientation) {
  LinearLayout linearLayout = new LinearLayout(_context);
  linearLayout.setPadding(16, 16, 16, 16);
  linearLayout.setOrientation(orientation);
  return linearLayout;
 }

 @SuppressWarnings("deprecation")
 private Spinner GenerateSpinner() {
  Spinner spinner = new Spinner(_activity);
  LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
    LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
  spinner.setLayoutParams(layoutParams);
  return spinner;
 }

 public void Popup() {
  Builder alertDialogBuilder = new AlertDialog.Builder(_activity);
  View view = GenerateLayout();
  alertDialogBuilder.setView(view);
  alertDialogBuilder.setPositiveButton("OK",
    new DialogInterface.OnClickListener() {
     @Override
     public void onClick(DialogInterface dialog, int which) {
      Log.e("TEST","OK");
     }
    });
  alertDialogBuilder.setNegativeButton("Cancel", null);
  Dialog alertDialog = alertDialogBuilder.create();
  alertDialog.show();
 }

 private View GenerateLayout() {
  LinearLayout linearLayout = GenerateLinearLayout(LinearLayout.VERTICAL);

  LinearLayout messageLinearLayout = GenerateMessageLayout();

  linearLayout.addView(messageLinearLayout);

  return linearLayout;
 }

 private LinearLayout GenerateMessageLayout() {
  LinearLayout linearLayout = GenerateLinearLayout(LinearLayout.HORIZONTAL);
  _spinner = GenerateSpinner();
  _spinner.setAdapter(new CityAdapter(_activity)); 
  _spinner.setSelection(0);
  linearLayout.addView(_spinner);
  return linearLayout;
 } 

 private class CityAdapter extends BaseAdapter implements SpinnerAdapter {

  private Context _con=null;
  private String[] _cities=null;
 
  public CityAdapter(Context context)
  {
   _con=context;
   _cities=_con.getResources().getStringArray(
     R.array.cities);
  }
 
        @Override
        public int getCount() {
         if(_cities==null)
         {
          return 0;
         }
            return _cities.length;
        }

        @Override
        public Object getItem(int position) {
         if(_cities==null||_cities.length<=0)
         {
          return null;
         }
            return _cities[position];
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

 
  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
   TextView textView=new TextView(_con);
   textView.setTextColor(Color.BLACK);
   textView.setTextSize(20);
   textView.setText(_cities[position]);
   return textView;
  }

 
    }

}

注：

1、spinner和AlertDialog的new需使用activity，使用context將在彈出下拉菜單時造成錯誤。

2、_con.getResources().getStringArray(R.array.cities)是加載xml中定義的數組。

city.xml(位於values文件夾下)

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string-array name="cities">
        <item>廈門</item>
        <item>北京</item>
        <item>上海</item>
    </string-array>

</resources>

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